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Full text of "Treatise On Applied Analytical Chemistry(Vol-1)"

SPECIAL BRONZES

239

The compositions of the commoner commercial types of manganese-bronzes
are as follows  (Guillet) :

TABLE XXVI
Composition of Manganese-bronzes


	
	
	

I
	92
	8                —       :        i
	

2
	•   i          84
	14                             —                            2
	—

3     •     •
	.   i          82
	15                    —                   3
	—

4     .     .
	92
	8                    3                   0-5
	trace

Nickel -bronzes

The addition of small proportions of nickel to bronzes increases the
hardness and lustre and imparts a pleasing, golden colour.
Their analysis includes :

1.  Determination of the Tin. — -2 grams of the sample are treated
in a covered, tall, narrow beaker with 20 c.c. of nitric acid (D 1-2), the
solution being evaporated to dryness, taken up with a few drops of nitric
acid and hot water and heated for a short time on the water-bath.   The
metastannic acid is collected on a close filter-paper and, being  in small
quail tity, may be weighed directly after washing with hot water acidified
with nitric acid, drying and calcining.

2.  Determination of the Lead, Copper, Iron, Nickel and Zinc. —
These elements are determined in the liquid freed from metastannic acid
by the methods given for the analysis of argentan (see later).

3.  Determination of the Phosphorus, Arsenic and Sulphur. — See
Ordinary Bronzes.

Nickel-bronzes have the following mean composition :   88-89% Cu, 2-3%
Sn,  6-7% Zn, 2-3% Ni, and 0-1-0-3% Pb-

Lead-nickel-bronzes

These are very soft and are also called plastic bronzes and serve mostly
as antifriction metals.   Their analysis comprises :

1.  Determination of the  Tin.—2 grams of the alloy are dissolved
in a covered, tall, narrow beaker with 20 c.c. of nitric acid (D 1-3), the solu-
tion evaporated to dryness, and the analysis continued as with ordinary
bronzes (q.v.).

2.  Determination of the Lead.—The solution freed from metastannic
acid and the solution of the oxides of copper and lead retained by the meta-
stannig acid are evaporated together to a small volume and then heated with sulphuric acid and the separate determinations carried